Conditional Probability and Components of RT in the Variable Foreperiod Experiment

Abstract

If the passage of time during the foreperiod in a variable foreperiod experiment is marked by a series of tones, RT decreases with the conditional probability of stimulus occurrence. RTs at short foreperiods, however, are rather slower than would be expected on the basis of a simple conditional probability effect. It is suggested that this is attributable to an independent “initial slow reaction” effect, and it is shown that the degree of this effect is influenced by the duration of the prior foreperiod. The results are related to those of variable foreperiod a-reactions in which no conditional probability effect has been found, and it is argued that in a marked reaction of the kind described above, the initial slow reaction effect behaves like an a-reaction component of RT. It is suggested that the absence of a conditional probability effect in the a-reaction and its presence in the marked reaction are related to the fact that a different type of sensory process is used to identify the signal in each case.

Reweighting sequential effects across different distributions of foreperiods: Segregating elementary contributions to nonspecific preparation

“…Unfortunately, Trillenberg et al (2000) did not report sequential effects. Instead, they went on to show that RT decreases linearly with an increasing conditional probability of S 2 occurrence (see also Stilitz, 1972). However, as long as the contribution of sequential effects is not taken into account, this finding does not warrant the inference that the conditional probability also determines the state of nonspecific preparation.…”

Intentional and unintentional contributions to nonspecific preparation during reaction time foreperiods.

“…Initially, it was assumed that expectancy strongly correlates with the objective conditional probability of IS presentation, which is low at the start of a trial and increases as time goes by without IS presentation. The corresponding growth of expectancy is assumed to enhance the participant's preparatory state, which in turn speeds responding (Baumeister & Joubert, 1969;Drazin, 1961;Niemi & Naatanen, 1981;Requin & Granjon, 1969;Stilitz, 1972). Thus, time uncertainty along with expectancy in terms of the conditional probability of IS presentation provides an adequate explanation for FP effects on mean RT in both pure and mixed blocks, and consequently these concepts have found general acceptance in the literature (e.g., Luce, 1986;Sperling & Dosher, 1986).…”

Time perception and word recognition: An elaboration of the time-criterion account

“…Indeed, there is. In particular, research on the effects of foreperiod duration on stimulus latencies provides nice support for the idea that participants are continually monitoring time during the performance of speeded tasks (e.g., Grosjean, Rosenbaum, & Elsinger, 2001;Niemi & Näätänen, 1981;Requin, Granjon, Durup, & Reynard, 1973;Stilitz, 1972). For example, Grosjean et al examined the effect of changing the time at which a stimulus occurred, presenting it either earlier than expected or later than expected.…”